Red, robust, and a little rowdy
The serpae tetra packs more colour and more attitude per inch than almost any beginner fish. A rich red body, a dark shoulder blotch, and black-and-white edging on the fins make a school of them look like drifting embers, and on pure keeping terms they are easy: hardy in a cycled tank, unfussy eaters, tolerant of ordinary community water. The reason this species comes with an asterisk is behaviour. Serpaes are the tetras most often behind mysteriously shredded fins on other fish, and whether you meet that side of them depends almost entirely on decisions made at purchase.
Group size is the behaviour switch
Serpaes live in a constant, sparring hierarchy, flashing and chasing to sort out who stands where. In a school of eight or more — ten is better — that sparring is a closed loop: there is always another serpae to posture at, and tankmates are ignored. In a trio, the loop has too few exits, and the fish redirect onto the nearest slow target, nipping fins in passing until a gourami or angelfish is genuinely damaged. This is why the same species is described online as both peaceful and a menace: both reports are true, of different group sizes. A twenty-gallon or longer tank gives the school room to run its politics without involving the neighbours.
Tankmates: choose fish that can shrug it off
Serpaes live well with their own kind — other robust, mid-sized tetras, barbs, danios, rainbowfish, and corydoras on the bottom all hold their own. The combinations to avoid are slow fish with long, flowing fins: fancy guppies, bettas, angelfish, and long-finned varieties of otherwise suitable species, plus very small, timid fish that will be stressed by the school's constant motion even without contact. If you already dream of an angelfish centrepiece, choose a different tetra now rather than rehoming fish later; serpaes are a commitment to a lively style of tank, and within that style they are superb.
Feeding and everyday care
Nothing in serpae care is exotic. They take flake, micro-pellets, and frozen foods eagerly from mid-water, colour deepest on a varied diet that includes small meaty frozen items, and benefit from the standard rhythm of a cycled filter and weekly partial water changes. Plants, wood, and a darker background set the red off and give lower-ranking fish somewhere to step out of the sparring. Because they are bold feeders, they suit a beginner who wants visible, responsive fish rather than ones that need coaxing — the school will meet you at the glass within days of settling.
Solving problems the serpae way
If fins start fraying on tankmates, resist the urge to treat for fin rot first: watch the tank at feeding time and in the morning, and if the serpaes are the culprits, the remedy is structural — more serpaes, more space, or rehoming one side of the mismatch — not medication. Genuine health issues in this hardy fish are uncommon; a serpae that pales, stops sparring, and leaves the school deserves a water test and, if it does not recover quickly, advice from an aquatic veterinarian. Keep honest notes on what your school lived with successfully, because KinsLe's Transferrable Profiles pass that proven tankmate record along if the fish are ever rehomed.